Transducers of acoustic energy in a liquid medium are many and varied in design. The selective projection and reception of acoustic energy over a broad frequency spectrum has been actively pursued with the varying results. Processing low frequency acoustic energy generally has dictated that the dimensions of the transducer be very large since the dimensions of the transducer are preferably in the order of a half wave length of the lowest frequency of interest. Thus, frequencies as low as ten Hz call for having a huge, ponderous transducers that are not only difficult to handle but are expensive. There are a good number of small transducers which exhibit a satisfactory response in the higher frequency ranges but are unable to function satisfactory at lower frequencies. The smaller transducers are more manageable and are not overly expensive. Designers long have sought to use these smaller transducers for low frequency operation but, largely, have been disappointed. In one approach a number of compliant bags are placed in the transducer's proximity or the transducer's housing is enlarged to have internal gas volumes communicating with a projection surface. Both of these approaches call for adding expensive, hard to fabricate or machine structures which boost the price and increase the bulk of the modified transducers. Thus, there is a continuing need in the state-of-the-art for an improvement for a transducer which is not overly expensive and gives a capability for transmitting a broad band of acoustic energy that embraces the lower frequency spectrum.